This invention relates to bonding of fully-fabricated semiconductor devices onto other fully-fabricated semiconductor devices so as to produce integrated units, and particularly to bonding fully-fabricated photonic elements, such as GaAs/AlGaAs multiple quantum well (MQW) modulators, onto fully-fabricated integrated circuit (IC) chips such as Si or even GaAs.
Integration of photonic devices with silicon IC chips makes it possible to combine the advantages of each. Among photonic devices, GaAs/AlGaAs multiple quantum well (MQW) modulators are particularly beneficial as input/output (I/O) elements on IC chips because they have a high absorption coefficient of light and can serve as both receivers and transmitters. They typically operate at an optical wavelength (xcex) of 850 nm (nanometers).
The aforementioned applications Ser. No. 083,784, filed Jun. 25, 1993, Ser. No. 08/236,307, filed May 2, 1994, and Ser. No. 08/366,864 filed Dec. 30, 1995, disclosed methods of bonding a photonic element, such as a GaAs/AlGaAs (MQW) modulator, to an IC chip by bonding their respective terminals to each other, filling the interiors between them with photoresist or a photoresisting cement, and then removing the substrate of the photonic device. Ser. No. 08/366,864 specifically discloses wicking a cement, such as epoxy into the interstices in place of the photoresist. However, voids that extent to one or both substrates sometimes form in the cement. These may allow that etch that removes the substrate on the modulator to affect other parts of the combined unit.
An embodiment of the invention involves confining the surface of the substrate with an etch-resist before bonding the conductors of one fabricated semiconductor device having a substrate to the conductors on another fabricated semiconductor device having a substrate, flowing an uncured cement between the devices, allowing the etch-resist to solidify, and removing the substrate from one of the semiconductor devices.
The various feature of novelty which characterize the invention are pointed out in the claims. Objects and advantages of the invention will become evident from the following detailed description when read in light of the accompanying drawings.